F.3 recirculating ball system that was standard fitment on the 420, and 3-1/4 turns for the constant ratio Burman power steering system optional on the 420's predecessor, the Jaguar S-Type. Whilst advanced for its time, the Variomatic system did have certain drawbacks. It was more complicated and expensive than a constant ratio power assisted system. The Variomatic system was also criticised for feeling too light at high speed, when greater weighting tends to give the driver more confidence in making fine steering adjustments. Later systems by other manufacturers would adjust the behaviour of the steering in reaction to road speed. Crown bottle top Henry Marles also patented an improved crown bottle top in 1906 and bottles no longer required a special opener. References Further reading Link to Magal Adwest Western Thomson website External links US patent 1584629 A US patent 1720911 A Automotive steering technologies